The present invention relates to an improved apparatus for automatically inserting various types and sizes of electronic components having axially extending lead wires into predetermined apertures in a printed circuit board. Specifically, the apparatus of the present invention includes a lightweight, compact insertion head which has automatically adjustable pairs of cutting, bending and insertion tools to enable the machine to first cut and bend the axially extending lead wires and then to automatically insert components having different bent lead spacings into the proper location on a printed circuit board.
Automatic electronic component insertion apparatus are well known. Conventional apparatus for continuously and automatically inserting different types of electronic components having axially extending lead wires such as resistors and diodes, can be classified into two categories; those having fixed insertion tools and those having adjustable insertion tools. Each of these categories can be further divided into two sub-categories according to the way the electronic components are fed into the apparatus. One sub-category of machines feeds the different types of electronic components arranged in a preset order, for example, on a taped band, to the insertion head for successive insertion. The second sub-category of insertion machines utilizes a plurality of feed assemblies, with each assembly including one type of electronic component. The appropriate component is then successively selected in the order of insertion and conveyed to the insertion head by a belt, pipe or other means.
The former sub-category has the disadvantage that since the different electronic components are arranged sequentially in taped, banded form in the order of insertion, if a failure of insertion occurs, if the next component is merely inserted the order of insertion will be incorrect. Such disadvantage is not present in the second sub-category of machines having a plurality of feed assemblies since each feed assembly has only type of component. Therefore, it is possible to merely feed the next component from the same feed assembly. However, a disadvantage of some machines using a plurality of feed assemblies is that the insertion head structure is so large or complex that the components must be fed to the insertion head by conveyor or tube. Such transfer tends to cause rotation or tilting of the components making it difficult to feed them into the insertion head in a stabilized manner. Further, transfer by tube or conveyor often results in a time delay that affects the remainder of the feed cycle or, if parts are prefed and arranged in the order of insertion, in the tube or conveyor so they are immediately available, by virtue of the prefeeding, the same disadvantage as found in the sequential feed machines will be present.
New types of insertion appatus which eliminate the drawbacks of both sub-categories of machines are available. For example, the apparatus disclosed in U.S. Pat. No. 4,205,433 has a compact insertion head which can be mounted directly adjacent a component feed assembly which includes means for arranging and holding a plurality of taped assemblies of the same type of electronic components and means for moving one of the component feed assemblies to a predetermined component feed position in response to an instruction. The compact insertion head is adapted to travel between the component feed position and a second position adjacent to a printed circuit board. The insertion head directly receives a single electronic component cut off from the electronic component assembly. The insertion head moves to the second position where the axial leads of the component are bent and the component is inserted into the printed circuit board.
A disadvantage of the apparatus of U.S. Pat. No. 4,205,433 is that it has fixed insertion tools and cannot readily insert different types of components having body portions of different shapes and size or lead wires of different diameters since the distance between the leads (or the "lead pitch") after bending is not the same for all components due to such variables in component and lead dimensions. Thus, when it is desirable to insert different types of electronic components in a continuous process, such equipment cannot be used. Instead, component insertion apparatus having adjustable insertion tools must be utilized.
U.S. Pat. No. 3,167,780 discloses a component insertion apparatus in which the insertion head is adjustable to enable the apparatus to insert components having different spacing between their bent leads. Specifically the adjustment is accomplished by replacing the inserting tools and changing the spacing of both pairs of cutting and bending tools relative to the centerline by activating adjustment screws manually. The disadvantage of such apparatus is that the machine must be stopped, disassembled and reassembled before components having different bent lead spacing or pitch can be inserted.
U.S. Pat. No. 2,982,967 discloses a component insertion apparatus which has a split or two-part insertion tool which initially bends and thereafter inserts the bent leads into corresponding holes in a printed circuit board. The insertion is followed by cutting and clinching of the inserted lead ends from the underside of the printed circuit board. Because the apparatus utilizes a split or two-part insertion tool, the pairs of ganged bending and inserting tools can be adjusted relative to each other to achieve the desired lead and hole spacing. The adjustment is accomplished by a single lead screw having oppositely threaded sections which may be manually adjusted by turning one or the other of the adjustment knobs. Such adjustment causes both parts of the insertion tool to move about the centerline. Since the adjustment of the tool spacing must be made manually, the apparatus is not automatic.
U.S. Pat. No. 3,078,466 discloses an adjustable component inserting machine in which the lead cutting operation occurs after the leads have been bent and inserted through the preformed holes in the printed circuit board. In this apparatus, one set of lead working tools (including the lead bending tool and the lead end inserting tool) is adjustable laterally while the other set of lead working tools is stationary. Although the apparatus of this patent moves one set of lead working tools on an automatic basis and in accordance with a program which is predetermined and set up for a particular board design or configuration, since one set of lead working tools is stationary, it is not possible to locate the components of the printed circuit board in their optimum positions. The same disadvantage is present in the apparatus which is the subject of Japanese Patent Publication No. 28604/1964. This publication discloses an adjustable arrangement for varying the pitch of the lead wires to be inserted into apertures in a printed circuit board. The apparatus comprises a pair of forming elements for bending lead wires to form parallel ends wherein one of the elements are fixed and the other is moveable.
Another adjustable component insertion equipment is disclosed in U.S. Pat. No. Re. 27,968 (formerly U.S. Pat. No. 3,539,086). Such apparatus is constructed to insert different types and sizes of electronic components delivered to the insertion head in the order of insertion in banded form. The insertion head has cutting, bending and insertion means which are adjustable relative to each other to accomodate electronic components which should be shaped with different lead pitch. The spacing between the tools is adjusted by a motor mounted on the insertion head itself. Such apparatus has the disadvantage of having a large and complex head resulting from the placement of the motor on the insertion head and has the additional disadvantage inherent in machines having sequential feeders wherein the electronic components are fed from a single taped band in sequential order.
Accordingly, there is a need for an adjustable electronic component insertion machine which is automatically adjustable, yet has a compact design because it does not have the motor mounted on the insertion head, can feed components which are delivered directly to the insertion head at random rather than in fixed sequential arrangement has an insertion head which has insertion tools which are both adjustable relative to the centerline.
There is a further need for an adjustable electronic component insertion machine which is capable of inserting components into a printed circuit board in an orientation rotated through a predetermined angle (e.g. 90.degree.) about an axis perpendicular to the plane of the printed circuit board without having to change the orientation of the printed circuit board itself. Necessarily, such equipment must have an insertion head which is capable of rotating about an axis perpendicular to the plane of the printed circuit board while the printed circuit board remains fixed.